Reducing unequal biasing in solar cell testing

Abstract

A solar cell testing apparatus can include a first electrical probe configured to receive a first voltage at a first location of a solar cell. The solar cell testing apparatus can also include a second electrical probe configured to receive a second voltage at a second location of the solar cell, where the second location is of the same polarity as the first location.

What is claimed is: 
     
         1 . A solar cell testing apparatus, comprising:
 a first electrical probe configured to receive a first voltage at a first location of a solar cell;   a second electrical probe configured to receive a second voltage at a second location of the solar cell, wherein the second location is of a same polarity as the first location.   
     
     
         2 . The solar cell testing apparatus of  claim 1 , wherein the first and second locations are first and second contact pads, respectively. 
     
     
         3 . The solar cell testing apparatus of  claim 1 , further comprising a switch configured to switch between the first or second electrical probe. 
     
     
         4 . The solar cell testing apparatus of  claim 3 , wherein the switch comprises an electrical switch. 
     
     
         5 . The solar cell testing apparatus of  claim 4 , wherein the electrical switch is programmed to cycle periodically, allowing for the measurement of voltage values at different locations periodically. 
     
     
         6 . The solar cell testing apparatus of  claim 1 , further comprising:
 a third electrical probe configured to receive a third voltage at a third location of the solar cell, wherein the third location is of the same polarity as the first and second location.   
     
     
         7 . The solar cell testing apparatus of  claim 1 , wherein the solar cell testing apparatus is an electro-luminescence tester, photo-luminescence tester, hot spot tester, current-voltage (IV) tester, or a laser-beam induced current tester. 
     
     
         8 . A solar cell testing apparatus, comprising:
 a first electrical probe configured to receive a first voltage at a first location of a solar cell;   a second electrical probe configured to receive a second voltage at a second location of the solar cell, wherein the second location is of a same polarity as the first location; and   a first feedback circuit coupled to the first and second electrical probes, wherein the first feedback circuit is configured to reduce a voltage potential between the first and second locations.   
     
     
         9 . The solar cell testing apparatus of  claim 8 , wherein the first feedback circuit comprises:
 a differential amplifier configured to convert a voltage difference between the first and second voltages to an amplified voltage signal; and   a feedback element configured to receive the amplified voltage signal, and supply a current to the solar cell that reduces the voltage potential between the first and second locations.   
     
     
         10 . The solar cell testing apparatus of  claim 8 , further comprising:
 a third electrical probe configured to receive a third voltage at a third location of the solar cell, wherein the third location is of the same polarity as the first and second location; and   a second feedback circuit coupled to the first and third electrical probes, wherein the second feedback circuit is configured to reduce a voltage potential between the first and third locations.   
     
     
         11 . The solar cell testing apparatus of  claim 8 , wherein the solar cell testing apparatus is an electro-luminescence tester, photo-luminescence tester, hot spot tester, current-voltage (IV) tester, or a laser-beam induced current tester. 
     
     
         12 . A method for testing a solar cell, the method comprising:
 applying a load to a solar cell;   a first feedback circuit reducing a voltage potential, dependent on the load, between a first and second location of the solar cell; and   a first voltage probe receiving a first voltage at a first location of the solar cell.   
     
     
         13 . The method of  claim 12 , further comprising:
 a second voltage probe receiving a second voltage at a second location of the solar cell.   
     
     
         14 . The method of  claim 13 , wherein the second voltage is received simultaneously with the first voltage. 
     
     
         15 . The method of  claim 13 , wherein the second voltage is received 1-100 micro-seconds after the first voltage. 
     
     
         16 . The method of  claim 13 , wherein reducing the voltage potential comprises:
 converting a voltage difference between the first and second voltages to an amplified voltage signal; and   adjusting a signal of the feedback circuit based on the amplified voltage signal.   
     
     
         17 . The method of  claim 16 , wherein the adjusting the signal comprises adjusting an output current of the feedback circuit based on the amplified voltage signal. 
     
     
         18 . The method of  claim 17 , further comprising:
 supplying the output current to a second location of the solar cell, wherein supplying the output current to the second location results in an adjusted total voltage of the solar cell.   
     
     
         19 . The method of  claim 12 , further comprising determining a residual error of a voltage difference between the first and second voltages. 
     
     
         20 . The method of  claim 12 , wherein applying a load comprises applying an electrical load, a resistive load, exposing the solar cell to light, applying a current or applying a laser to the solar cell.